Why is my RemoteFunction printing nil?

LocalScript:

local player = game.Players.LocalPlayer
local UIS = game:GetService("UserInputService")

local debounce1 = true
local animation = game.ReplicatedStorage.anims.shoot

UIS.InputBegan:Connect(function(key, gameproccessed)
	if key.UserInputType == Enum.UserInputType.MouseButton1 then
		if debounce1 then
			debounce1 = false
			
			game.ReplicatedStorage.ClickEvent:FireServer(animation)
			
			local length = 			game.ReplicatedStorage.ClickEventReturn:InvokeServer(animation) -- where it fires from
			
			wait(length + 0.1)
			
			debounce1 = true
		end
	end
end)

Script:

function send(player, animation)
	print(player, animation) -- prints "nil nil"
	
	local track = Instance.new("Humanoid"):LoadAnimation(animation) -- errors
	
	print(track.Length)
	
	return track.Length
end

game.ReplicatedStorage.ClickEventReturn.OnServerInvoke = send()

This for some reason is printing nil, when i specified the argument in the localscript. And i assume the first argument would be the player. Whats wrong here?

Help pls

Thx